The Eurasian hot nightlife: Environmental forces associated with nocturnality in lizards

Abstract

Aim Lizards are ancestrally diurnal, and most of them remain so. Nocturnality is common among lizards, but the environmental factors associated with lizard nocturnal activity are still unknown. Here, we contrasted the ambient temperature and productivity hypotheses, where we predicted that cold temperatures will pose a stonger limit to nocturnal species richness than diurnal lizards. Moreover, we contrasted the relative importance of annual, day and night mean temperatures to pinpoint the drivers of nocturnal lizard richness. Location Mainland Eurasia. Methods We collected distribution range and activity time data for all 1,113 lizard species found throughout mainland Eurasia. This represents the largest geographical scope to date, for studies of lizard species richness. We examined the spatial patterns of nocturnal species richness in relationship to diurnal species richness across environmental gradients of ambient temperature and productivity. Results Nocturnal lizards are richest in the tropics and in deserts, and their richness decreases with latitude. However, nocturnal lizards are absent from the highest latitudes and coldest regions inhabited by lizards. Diurnal and nocturnal lizards respond in a similar manner to climatic factors. Ambient temperature has a strong influence on both, whereas productivity is more tightly related to the proportion of nocturnal species. Main conclusions Nocturnality is widespread among Eurasian lizards. However, nocturnal lizards are absent from invariably cold regions, and low temperatures seem to be a limiting factor for lizard activity period. We suggest that the year‐round warm nights of the tropics reduce the cost of being active at night and open the nocturnal niche for many lizards. In hot deserts, the combination of hot days and aridity increases the cost of diurnal activity, whereas nocturnal activity provides a shelter from these extreme conditions.

The global biogeography of lizard functional groups

“…As opposed to the other strategies, the nocturnal strategy is dominated by a specific clade – the Gekkota (Appendix S9), although it contains members of other clades as well (notably Australian Lerista skinks). This finding is compatible with previous studies that found that diel activity is highly phylogenetically conserved (Anderson & Wiens, ; Roll, Dayan, & Kronfeld‐Schor, ; Vidan et al, ). This raises two interesting questions for future research: (a) Why does nocturnality seldom occur in the New World; and (b) Why does nocturnality remain almost exclusively (94% of species) a gekkotan trait?…”

“…If richness patterns vary across groups as a function of the ecological traits of constituent species, deconstructing the total assemblage into functional groups may improve our understanding of the causes underlying richness variation (Kissling et al, ). For example, the deconstruction of Eurasian lizards by their activity time revealed substantial differences between the richness patterns of nocturnal and diurnal lizards (e.g., diurnal species range further north; Vidan et al, ). Species richness patterns may be deconstructed into richness of members of different functional and ecological groups that share similar traits and presumably respond similarly to environmental gradients.…”

“…Although several studies have examined regional lizard richness patterns (e.g., Hosseinzadeh, Aliabadian, Rastegar‐Pouyani, & Rastegar‐Pouyani, ; Kissling, Blach‐Overgaard, Zwaan, & Wagner, ; Lewin et al, , Tallowin, Allison, Algar, Kraus, & Meiri, ; Pincheira‐Donoso, Tregenza, Butlin, & Hodgson, ), the global richness pattern of all known lizard species has only recently been identified (Roll et al, ). Only a few studies have examined richness patterns by deconstructing them according to species' traits (by morphological traits: Scheibe, 1987; taxonomy: Powney, Grenyer, Orme, Owens, & Meiri, ; range size: Lewin et al, ; activity time: Vidan et al, ). Recently, multiple traits of 134 lizard species were used to arrange lizards along functional trait combination axes, showing that lizards display diverse and distinct life history strategies (Pianka, Vitt, Pelegrin, Fitzgerald, & Winemiller, ).…”

Extinct, obscure or imaginary: The lizard species with the smallest ranges

“…Nocturnality may make lizards more difficult to detect, possibly meaning that the recent increased rate of finding nocturnal TL‐species could reflect the increased use of head torches (which also resulted in finding new species of diurnal lizards, e.g., anoles and chameleons, which were detected sleeping on branches, e.g., Poe, Latella, Ayala‐Varela, Yanez‐Miranda, & Torres‐Carvajal, ). It may also reflect the propensity of geckos to have narrow ranges, tropical distribution and nocturnal behaviour (Gamble, Greenbaum, Jackman, & Bauer, ; Meiri, ; Vidan et al., ). Indeed, the propensity of geckos to specialize in using specific and naturally isolated substrates (usually rocks; e.g., Giri, Bauer, Vyas, & Patil, ; Grismer, ; Heinicke, Jackman, & Bauer, ; Oliver, Bourke, Pratt, Doughty, & Moritz, ; Oliver & Doughty, ; Pauwels & Sumontha, ; Wood et al., ) and speciate where these are found may often predispose them to have very small ranges.…”

Systematics of the Saharo‐Arabian clade of the Palearctic naked‐toed geckos with the description of a new species ofTropiocolotesendemic to Oman

“…The group includes a radiation of about 90 arid‐adapted species that have been able to colonize and thrive in some of the most inhospitable arid environments of the planet, which contrasts with their fragile appearance (Anderson, ; Baha El Din, ; Gardner, ; Metallinou, Vasconcelos, Šmíd, Sindaco, & Carranza, ; Metallinou et al., ; Schleich, Kastle, & Kabisch, ; Sindaco & Jeremčenko, ; Šmíd et al., ). Their diversity in arid regions has probably been facilitated by their nocturnal behavior (Gamble et al., ; Vidan et al., ). The phylogenetic relationships and taxonomy of this dominant group of Palearctic geckos were carefully revised by Bauer et al.…”